Light-transforming compositions and method of making same.



= orn ca PETER COOIER HEWITT, OF EINGWOOD MANOR, NEW JERSEY, ASSIGNOE, BY MES'NE ASSIGNMENTS, TO COOPER HEWITT ELECTRIC COMPANY, OF HOBOKEN, NEW JERSEY, A CORPORATION OF NEW JERSEY.

LIGHT-TRANSFORMING COMPOSITIONS AND METHOD OF MAKING SAME.

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N0 Drawing.

To all whom it may concern:

Be it known that 1, PETER COOPER HEWITT, a citizen of the United States, and resident of Ringwood Manor, county of Passaic, State of New Jersey, have invented certain new and useful Improvements in Light- Transforming Compositions and Methods of Making Same, of which the following is a specification.

My invention relates to the class of devicesemployed for combining with rays of a source of light which is deficient in some desired portion of the spectrum, rays of other wave length produced by the transformation of certain rays or waves of one length into rays or waves of another length and of such character as to supply the ray or Wave length desired, within limits.

In a patent issued to me on December 22, 1908, bearing No. 907,598 and in a companion application Serial No. 453,187, filed by Inc September 15, 1908, I have described certain methods of producing and utilizing light rays of the character referred to, and my present invention relates more particularly to special compounds of materials to be used for transfonning light rays and, when desired, adding light waves of definite character to light from any source.

Retentiveness of the fluorescent quality, or durability of the property of transforming light, seems from experiment to be seriously modified by the internal structure or physical arrangement of the material in its final state. The material retains this light transforming property better and for a longer period by reason of its being or having been in a state of internal stress or by reason of the fact that the internal structure is fibrous in nature. It is important also that the conditions of drying or hardening of the material be properly carried out, as affecting the physical relation of the materials to each other during manufacturing and as afiecting the finished product.

In practice I find that, while several different materials and compounds may be used with greater or less efficiency and durability or retentiveness, most excellent results are obtained by the use of rhodamin combined in proper proportions with acetate of cellulose to which a medium adapted to create such a structure, such as glycerin, has been added. A combination or association Specification of Letters Patent.

Patented June 27, 1916.

Application filed July 23, 1910. Serial N 0. 573,557.

of the materials, having a structure retentive of the light transforming property under conditions of good efficiency and durability, can be secured in the foregoing manner. A varnish is formed consisting of 70% of acetate of cellulose; 10% of glycerin and of acetic acid, the above percentages being the percentages by weight. To this is added technical acetone to make a 12% solution. The acetate of cellulose, known in commerce as cellet may be used and prepared as follows: It may be first bleached with permanganate of potash made acid with sulfuric acid, and subsequently treated with sulfurous acid for further bleaching and removing the permanganate, and subsequently it is washed with water until free from salts. An amount of rhodamin, equivalent to three one-hundredths by weight of the weight of cellet and glycerin is added, the rhodamin being in solution in alcohol or acetonefor convenience. The whole forms a varnish which when dry may be used either for reflecting purposes or as a light screen or filter, that is' to say, it may be painted upon a suitable backing and when dry the transformed light reflected therefrom and mingled with the light from the source, or it may be made into a film or painted upon a proper transparent backing and placed wholly or partially around the source of light so that more or less of the original light and the transformed light will be mingled.

In an application filed by me September 18, 1909, Serial Number 518,325, I have described various forms of backings or supports for varnishesof this general character and also materials which may be mixed with the varnish for the purpose of increasing the light qualities thereof. When it is to be placed upon a backing or support to serve as a light reflector, I have found it advantageous to use as the immediate support for the varnish a material, such for instance, as calcimine or white lead, or other material having the characteristics of dispersing light. In some instances it may be desired to mix the light-dispersing material with the varnish.

The proportions above given may be modified to a reasonable degree, but those given above are found to produce a material hav- Y the drying of the material, the acetic acid and acetone evaporate, leaving the acetate of cellulose the coloring matter and an amount of glycerin as the light transformer. The varnish may be painted upon a suitable temporary support and dried and then stripped off from the support and used independently of any other support as the light reflector or screen. Any desired number of coatings of the varnish may be painted upon the support in succession. I have found, for instance, that five coats quickly flowed, one after the other, gives a very eflicient result.

The light transforming composition may well consist of the product of a mixture of approximately 90 to 95 per cent. of acetate of cellulose, to per cent-of glycerin, and 0.05 to 0.005 per cent. of rhodamin. Acetate of cellulose may be combined with appro'ximately two parts of acetic acid and one part of glycerin.

I claim as my invention:

1. A composition for forming a light transformer, containing acetate of cellulose, glycerin and rhodamin.

2. A composition for forming a light transformer, containing 90 to 95% of acetate of cellulose; 5 to 10% of glycerin, and 0.05 to 0.00534 of rhodamin.

3. The process of manufacturing a varnish for light transforming purposes, which consists in mixing approximately, 70% of acetate of cellulose, 10% of glycerin and of acetic acid, and then adding acetone to make approximately a 12% solution and rhodamin in the proportions of four onehundredths to four one-thousandths"substantially as described.

4. A composition for forming a durable light transformer, consisting of acetate of cullulose and a fluorescent dye-stuff, in combination with approximately two parts of acetic acid and one part of glycerin.

5. A light transforming composition containing a fluorescent dye-stuff, acetate of cellulose, and a medium adapted to create a structure capable of retaining the prop.

erty of fluorescence.

(i. A light screen composition containing a dye-stuff, acetate of cellulose, and a medium adapted to create a structure capable of increasing the property of color retention.

'7. A light screen composition containing a dye-stuff, acetate of cellulose, and a medium adapted to create a fibrous structure capable of increasing the property of color retention.

Signed at New York .in the county of New York and State of New York this 21st day of July A. D. 1910.

PETER COOPER HEWITT.

Witnesses:

' WM. H. CArnL,

Tnos. H. BROWN. 

